That’s a lot of questions there
For the books I use, I love Kanzen Master but it’s not for beginners at all. At my class I’m only recommending it for people who have finished Minna No Nihongo I, because there are a bunch of things it expects you to already know, and the explanations are quite short. Still, I love that book and it’s my main study material these days, but be warned if you go this route that at times you’ll have to look up more in-depth explanations on the internet because some points are left rather unexplained.
As for Minna No Nihongo, I’ll be honest: I don’t like it. The book seems far too drawn-out, often re-explaining things or using contrived ways of explaining. For example, in lesson 29 or 30 it explains how “~て います” is used to describe the current state of something, for example a broken window. However, first, we are first introduced to the form all the way back in lesson 14 where it’s made clear that it’s continuous present and therefore would apply to the current state of something, making the whole grammar point redundant. Second, at least in the Spanish edition, the explanation goes something like “~て います is used to point out the current state of something as the result of an action taken by someone in the past, and not a current action being taken in the present”, which to be honest is horribly contrived.
I really don’t like it, but it’s what we use in classes and at the moment I’m just using it to help cement stuff I’m learning with Kanzen Master.
As for where I take my lessons, it’s with a local teacher, which is quite lucky. I live in a small city among the Andean mountains, yet in here of all places there’s a (very small) Japanese community, among them one of the few Japanese teachers in the country (who’s also a native). Lessons are 3 hours, but they’re not too heavy since we’re mostly left to do stuff on our own, advancing at our own pace, the teacher being there to explain to us whenever we need help.
As for video games, I actually started playing them regularly (in Japanese) back in December, and they’ve been both a good source of new vocabulary and a nice way of measuring how much I’ve been learning since you can see how you understand more and more each day. I wouldn’t recommend them as your only study source, but they’re good to entertain you while also reinforcing some knowledge and allowing you to acquire some vocabulary. Mostly, they help immerse you on the language.
As for what’s the most important, I’d say WaniKani/Anki/Textbooks. It’s impossible to understand a book, or a game, if you can’t understand the grammar or if you have to look up every second word on a dictionary. The overreliance in the dictionary is common in the beginning, but ideally it should go down as your knowledge builds up and it’s great when you find yourself reading several sentences in a row on a non-textbook setting and understanding them without having to look anything up. As expected, tho, the reading and playing help reinforce what you learn through the textbooks, so they help each other. But the proper study is always the main thing here.
I don’t have any test results yet, though I did take N4 and failed about five years ago I only started studying more seriously last December, tho. Hopefully I’ll be able to take N3 next year, although considering it implies traveling (they don’t host the test on my city) I might skip it. That’s why I skipped out of N4 this year too, traveling in this country is quite annoying (and dangerous) :\